Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$219.56	6.533%	$233.9039	$233.90	$233.90	$233.90
Purchase #2	$165.32	6.514%	$176.0889	$176.09	$176.10	$176.10
Purchase #3	$83.34	7.789%	$89.8314	$89.83	$89.85	$89.80
Purchase #4	$216.31	5.467%	$228.1357	$228.14	$228.15	$228.10
Purchase #5	$199.74	6.483%	$212.6891	$212.69	$212.70	$212.70
Purchase #6	$41.44	8.839%	$45.1029	$45.10	$45.10	$45.10
Purchase #7	$85.67	7.331%	$91.9505	$91.95	$91.95	$92.00
7 purchase totals =	$1,011.38		$1,077.7024	$1,077.70	$1,077.75	$1,077.70